damn jeep

shes overheating, everytime i go 4wheelin have it in 4LO and go slow over rocks and stuff it goes up to like 220 and the reservoir water starts boiling and steaming, just put a new 195 thermostat in and the water in the resorvoir is always hot radiators hot so thermo is working and all the hoses are hot so water is being transfered, not sure why it does this though

89 xj 4.0L 5 speed

Mopar It said:

shes overheating, everytime i go 4wheelin have it in 4LO and go slow over rocks and stuff it goes up to like 220 and the reservoir water starts boiling and steaming, just put a new 195 thermostat in and the water in the resorvoir is always hot radiators hot so thermo is working and all the hoses are hot so water is being transfered, not sure why it does this though

89 xj 4.0L 5 speed

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Have you bled the system thoroughly? The closed system is notorious for air pockets.

no, could you give me a quick run through of how to drain everything?

i have an 89xj and had the same problem for the longest time. check these things out.

3 core raidator
coolent bottle Cap always goes bad
coolent bottle cracked
check lower hose, i put one from autozone and would still collapse, better to buy from the dealership with the spring inside so it wont collapse.

I hardwired the electric fan to a toggle switch cuz it wasnt working with the sensor.

Air bubble, try to burp system

Fan clutch no good

Switch to an open cooling system. It's really easy!!! Here is walk through. I would definitely consider it. When rebuilding my 90, it took 3 blocks to find one that hadn't been cracked due to the horrible closed cooling system and it came from a 1993. All you have to do is get a newer radiator with a cap, plug one hole of the factory coolant bottle and funnel the other one through a heater valve from a later generation.



That's what mine looks like. I just ran it 185 miles one way to norther Iowa to go camping at Backbone state park last week going 70-75 mph the whole way, climbing up and down all of the hills at the park, and never even passed 195. Definitely worth the $155 total for the conversion. My radiator was 130, the hoses are about 15, and the heater core is about $10 and you won't regret doing it.

Might want to make sure you don't have a blown head gasket or something though. Check to make sure it's not burning anitfreze by looking at the exhaust. If it smells sweet and burns white then you're burning antifreze. Other wise it might be soon enough to save it and swap to an open system

Just my 2 cents

Oh, you have to drill a hole in the top of the overflow bottle's cap as well. Forgot to mention that, but it's free so it doesn't make a huge deal.

ive never heard of a block cracking due to a cloded system. especially a renix block.

i second what other people have said. burp the system. search for 5-90's posts on drilling the thermostats, its a good read and quite helpful.

check your fan clutch.

also, i overheated not too long ago on the highway. i pulled over, noticed i boiled over. when i got home i checked absolutely everything. then i realised the fins on my condenser were bent and blocking virtually the entire radiator surface. took me a little over an hour to striaghten all those fins with a metal pick but it fixed my problem.

I don't know that it would directly and souly cause it to crack but it doesn't help. For 150 bucks you can fix it and not really have to worry about it anymore.

the renix closed system is as good as its weakest link. which in almost everyones case its almost 20 year old parts or low quality after market parts that replaced aging parts.

in my opinion an HO system is neither superior nor inferior, both system are in use today although closed systems are gaining popularity because nothing can get in to contaminate it.

diagnose the problem at hand. figure out how much it would cost to repair/replace it. and go from there.

i have a feeling sometimes the RENIX to HO cooling conversions are out of desparation to fix the problem by throwing parts at it.

but enough opinions. Mopar it, you should burp the system, when was the last time you flushed the system? is your radiator caked in a thin layer of mud/dirt? is the propellor on your water pump worn? i once read about the fins wearing out into nubs, being curious i pulled the water pump off my parts truck and found they had become rounded to a certain extent. do you or any of your friends own a temperature lazer gun? (if not i recall seeing ones at pepboys for under 40 bucks) check to see your radiator is actually cooling as the water passes through the channels. how old is your coolant pressure bottle/cap?

I wasn't throwing parts at it. I was putting a better system in while the engine is out. Anyway, if the Open isn't an option for you, then I would look at your overflow bottle. They are known to de-pressurize and cause over-heating. Next burp the system.